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MySQL Memory Consumption and Open Prepare Statements

Today I read the nice post of Bhuvanesh on the memory leak issue they experienced with MySQL. In fact when you read the post, you realize that MySQL was just following the parameters that were setup (the default of max_prepare_stmt_count is 16382 even on 5.6). I’m still convinced that the problem should be resolved in the application even if the … Read More

MySQL and Memory: a love story (part 2)

We saw in the previous post that MySQL likes memory. We also saw how to perform operating system checks and some configuration changes for Swap and NUMA. Today, we will check what MySQL server can tell us about its memory usage. Introduced in MySQL 5.7 and enabled by default in MySQL 8.0, the Performance_Schema‘s Memory instrumentation allows us to have … Read More

MySQL: size of your tables – tricks and tips

Many of you already know how to retrieve the size of your dataset, schemas and tables in MySQL. To summarize, below are the different queries you can run: Dataset Size I the past I was using something like this : But now with sys schema being installed by default, I encourage you to use some of the formatting functions provided … Read More

What is the best practice to get a list of all the queries running in MySQL (processlist) ?

If you are a MySQL DBA for a long time (like me), it’s very complicated to get rid of bad habits. One of them I really need to change is the way to retrieve the list of all the running queries (processlist). Usually, I use SHOW FULL PROCESSLIST which is very convenient, but like querying the Information_Schema, this statement has … Read More

How to know if a user never connected to the MySQL server since last boot ?

Performance_Schema is used most of the time to get metrics about queries and connections. But it can also provide other very useful information. So today, I will show you how you can see a list of users that didn’t connect to MySQL since we restarted it (since last reboot). SELECT DISTINCT mu.user FROM mysql.user mu LEFT JOIN performance_schema.users psu ON … Read More

I deeply value the diversity of MySQL developers, users, community and my blog readers. I cannot agree the suffering, oppression, and systemic racism the Black community faces every day. Black lives matter.